After his last available treatment, Kyrgios dropped eight of the last nine games to Millman, who missed nearly eight months with a hip injury.

"Nick’s shoulder deteriorated as the match went on," Millman said after his first US Open triumph. "It’s a victory but slightly hollow."

Austrian sixth seed Dominic Thiem finished off Aussie Alex de Minaur 6-4, 6-1, 6-1. Thiem is the highest-ranked rival to Federer and Nadal on their side of the draw.

"I’m not in the first row of favorites, maybe in the second, so I can play calm," Thiem said.Russian eighth seed Svetlana Kuznetsova, the 2004 US Open champion, rescued three match points in defeating 67th-ranked Czech Marketa Vondrousova 4-6, 6-4, 7-6 (7/2) to reach the second round.

Kuznetsova is among seven women who could become world number one after the US Open. So is Ukraine’s fourth-seeded Elina Svitolina, who held off 42nd-ranked Czech Katerina Siniakova 6-0, 6-7 (5/7), 6-3.

Also sustaining top spot hopes was seven-time Grand Slam champion Venus Williams, the US ninth seed who beat France’s Oceane Dodin 7-5, 6-4. This year’s Wimbledon and Australian Open runner-up is the field`s oldest woman at 37.

US Open 2017: Maria Sharapova battles on while Alexander Zverev, Nick Kyrgios crash out at US OpenDescription:Nick Kyrgios grabbed his right shoulder after a serve in the fourth game of the third set, having a ballboy grab his right arm to try and ease the pain at one stage.Times Now